Journal Article

Evaluation of humoral and cellular immune responses to BP26 and OMP31 epitopes in the attenuated Brucella melitensis vaccinated sheep

Zhang, Hui, Liao, Qingyu, Weng, Yunceng, Wang, Wenjing, Li, Chengyao, Qiu, Jinlang, Chen, Chuangfu, Allain, Jean-Pierre, Qiao, Jun, Wu, Jingbo

2014

Overview

•An attenuated Brucella melitensis vaccine M5-90 has been mostly used for animals in China.•Immune response to BP26 and OMP31 of the vaccine was evaluated in sheep.•Specific antibody and IFN-γ response were detected at low levels in vaccinated sheep.•Protective efficacy of the vaccine was overall weak and shortlived.•These data are helpful to design a safer and more effective B. melitensis vaccine. In recent years, the number of cases of human brucellosis has been increasing by approximately 10% per year in China. Most cases were caused by Brucella melitensis through contacts with infected sheep, goats or their products. An attenuated B. melitensis vaccine M5-90 is currently used to vaccinate both animals in China. This vaccine has not been investigated for critical parameters such as immune response and its association with protective efficacy. In this study, humoral and cellular immune response to the periplasmic protein BP26 and the outer membrane protein OMP31 were evaluated in M5-90 vaccinated Chinese merino and Kazak sheep. Antibodies to BP26 or OMP31 were detected at low levels, and specific IFN-γ response was quantified. Strongly reactive peptides derived from BP26 and OMP31 identified five T-cell epitopes (BP26-6, -8, -11, -12 and OMP31-23) common to both sheep species, five species-specific epitopes (BP26-10, -18, -21 and -22 and OMP31-12) and four animal-specific epitopes (BP26-15, -23, OMP31-6 and -21), which stimulated specific IFN-γ response in vaccinated sheep. Among those T-cell epitopes, reactivity to BP26-18 and -21 epitopes was significantly associated with MHC-I B allele (P=0.024). However, a specific T-cell response induced by the M5-90 vaccine was relatively week and did not sustain long enough, which might be suppressed by rapid activation of T-regulatory (Treg) cells following vaccination. These findings provide an insight in designing a safer and more effective vaccine for use in animals and in humans.

• Publisher: Elsevier Ltd,Elsevier,Elsevier Limited
• Subject: alleles / Allergy and Immunology / Amino acids / Animals / antibodies / Antibodies, Bacterial - blood / Applied microbiology / B. melitensis / Bacterial Outer Membrane Proteins - immunology / Bacteriology / Biological and medical sciences / BP26 / Brucella melitensis / Brucella Vaccine - immunology / Brucellosis / Brucellosis - immunology / Brucellosis - prevention & control / Brucellosis - veterinary / cell-mediated immunity / China / Epitopes / Epitopes, T-Lymphocyte - immunology / Female / Fundamental and applied biological sciences. Psychology / goats / humans / Immune Response / Immunity, Cellular / Immunity, Humoral / interferon-gamma / Interferon-gamma - immunology / Membrane Proteins - immunology / Merino / Microbiology / Miscellaneous / OMP31 / outer membrane proteins / Peptides / Proteins / Sheep / Sheep - immunology / Sheep Diseases - immunology / Sheep Diseases - microbiology / Sheep Diseases - prevention & control / Sheep, Domestic - immunology / T-lymphocytes / T-Lymphocytes - immunology / vaccination / Vaccine / Vaccines / Vaccines, antisera, therapeutical immunoglobulins and monoclonal antibodies (general aspects)